1. Field of the Invention
An aspect of the present invention relates to a digital broadcasting transmitter, a turbo stream processing method thereof, and a digital broadcasting system having the same. More particularly, an aspect of the present invention relates to a digital broadcasting transmitter which processes a normal stream and a turbo stream compressed in different formats from each other, a turbo stream processing method thereof, and a digital broadcasting system having the same.
2. Description of the Related Art
There are different digital broadcasting standards such as a U.S.-oriented advanced television system committee (ATSC) format and a European-oriented digital video broadcasting-handheld (DVB-H).
The U.S.-oriented transmission format is based on the National Television System Committee (NTSC) frequency band, and has the advantage of easily implementing a transmitter and receiver. The U.S.-oriented transmission format is a single carrier wave amplitude modulation vestigial side band (VSB) format, that is, this format can transmit high-quality video, audio and auxiliary data in the single 6 MHz bandwidth.
In the U.S.-oriented transmission format, an image signal is compressed in a moving picture experts group-2 (MPEG-2), a sound and voice signal is compressed in digital audio compression (AC-3), and the VSB technology is used to transmit such signals.
The reason why the image signal and the sound and voice signals are compressed in the MPEG-2 and AC-3, respectively is to reduce the bit rate of the image, voice and digital auxiliary data stream.
In the U.S.-oriented transmission format, the MPEG-2 used to compress an image signal has been developed for instances when a channel bandwidth or a storage capacity of a storing medium are limited, and when efficient transmission structure is needed. The MPEG-2 is a compression format which is interoperably designed with the asynchronous transfer mode (ATM) transmission structure.
Conventionally, only normal streams are used, but recently a dual transport stream adding a turbo stream with enhanced coding to the normal stream is used.
In this case, the compression performance and image quality of the turbo stream which is compressed in the conventional MPEG-2, is considerably decreased. Accordingly, the load on a transmission system and operating expenses of a broadcasting station are increased.